炭疽暴发疫情中炭疽病例诊断方法应用与建议

Methods for diagnosis of anthrax in outbreaks: application and recommendations

目的总结分析内蒙古自治区(内蒙古)炭疽暴发疫情中炭疽病例诊断方法的应用经验和问题,为炭疽预防控制工作提供参考。方法用载玻片直接蘸取和无菌棉签擦取疑似炭疽病例皮损渗出液,同时采集疑似病例静脉血标本。涂片镜检、直接分离培养、肉汤增菌后分离培养炭疽菌、炭疽芽胞杆菌实时荧光定量PCR扩增(毒素质粒的pagA、染色体rpoB、荚膜质粒的cap)以及ELISA法检测双份血清炭疽抗体。结果 2018年8月,内蒙古通辽市疾病预防控制中心实验室共采集17例炭疽病例标本,采集时间距发病时间最短1 d,最长16 d,中位数为6 d。15例可疑病例用过抗生素后采集标本(15/17,88.24%)。从1份标本中分离到炭疽芽胞杆菌,分离阳性率为5.88%(1/17);实时荧光PCR检测17份标本,阳性率为41.18%(7/17);ELISA检测保护性抗原抗体阳性率为83.33%(10/12)。结论在最佳时间采集标本是疫情早期定性的关键。推荐炭疽疫情中应用快速灵敏的实时荧光PCR检测诊断方法,应采集所有可疑病例双份血清提高病例诊断率。

Objective To analyze and summarize the experiences and problems in diagnosis of anthrax in outbreaks,and to provide a basis for anthrax prevention and control.Methods Lesion exudates were collected from suspected anthrax patients using slides and sterile cotton swabs and venous blood samples were also collected from suspected cases.Smear microscopy,direct culture,and broth enrichment were used to isolate and culture Bacillus anthracis.Real-time PCR was used to amplify the genes such as pagA in the virulence plasmid,rpoB in the chromosome,and cap in the capsule plasmid.Enzyme-linked immunosorbent assay(ELISA)was used to detect double serum anthrax antibodies.Results A total of 17 specimens were collected in the laboratory of the Center for Disease Control and Prevention of Tongliao,Inner Mongolia,China,in August 2018.The time window between disease outbreak and sample collection was 1 day at least and 16 days at most,with a mean of 6 days.In the 17 suspected patients,15(88.24%)received antibiotic treatment before sample collection.Bacillus anthracis was isolated from 1 specimen,yielding a positive rate of 5.88%(1/17).The real-time PCR analysis of all the specimens gave a positive rate of 41.18%(7/17).The results of ELISA showed a positive rate of 83.33%(10/12)for the protective antibody.Conclusion The optimal time to collect samples is the key to the early identification of outbreak.Real-time PCR,which is a fast and sensitive approach for diagnosis,is recommended for application in anthrax outbreak.Double serum specimens should be collected from all the suspected patients to increase the diagnosis rate.